| 1 | IOE | Island Oil Exploration Limited | Callsign: Island Oil, | STP | AVCODES |
| 2 | IOEP | I O EXPRESS INC | | | SCAC4 |
| 3 | IOER | Indiana & Ohio Rail System | eliminated 10/1994 | | NAKINA |
| 4 | IOER | The Indiana & Ohio Eastern R.R., Inc. | added 1/1988; 1/1994 | | NAKINA |
| 5 | IOER | The Indiana & Ohio Eastern R.R., Inc. | added 1/88; 1/94 | | NRHS |
| 6 | IOER | Indiana & Ohio Rail System | eliminated 10/94 | | NRHS |
| 7 | IOER | RETIRED 01-05-94 ATP (979) [INDIANA & OHIO EASTERN RAILROAD] | | | PWRC |
| 8 | IOER | INTER-ONTARIO EQUIPMENT RENTAL & RE | | | SCAC4 |
